Multiples of 10.
Is that what you are asking?
Try this way:
Note,
1. that 16/2=8 it means 10/2=5.
2. that 10*3=30, it means 16*3=48
Finally for whole table:
================
forks: 16 8 48
================
spoons: 10 5 30
================
Additive inverses combine to get 0. So, k is -1.4. The sum is 0. Hopefully that will help.
set up a ratio to find the length:
15/12 = DE/16
cross multiply the 15 & 16:
15 * 16 = 240
divide that by 12 to get DE
240 / 12 = 20
DE = 20